''We had a sweep on when the reactor would reach its critical point,'' Mr Palmer said.

More than half a century later, the work of the Australian Nuclear Science and Technology Organisation, as it is now called, had moved far beyond its original mission to enrich uranium and develop nuclear power, said the organisation's chief executive, Adi Paterson.

''People quickly learnt you could do great physics with these reactors and they started taking spare neutrons out of the reactors to [study] biological samples and mineralogy,'' he said.

In the 1960s the facility began producing radiopharmaceuticals and, before long, doses of radioisotopes were used by hospitals around Australia for medical imaging.

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Today ANSTO'S newer reactor, OPAL, produces, among other things, most of Australia's nuclear medicine. If you have ever had a heart or bone scan here, the radioisotopes were probably produced at this facility.

In the next five years the organisation aims to produce 25 per cent of the world's key isotopes for medical diagnosis and cancer treatment, about 15 million doses a year.

ANSTO's senior system engineer, Jasmin Craufurd-Hill, knows first hand the contribution radiopharmaceuticals play in modern medicine.

Ms Craufurd-Hill, her father and grandmother have all required medical procedures that used radioisotopes. ''That's three generations of my family who have benefited from ANSTO,'' she said.

Beyond nuclear medicine, ANSTO's particle accelerator is used to help solve some of science's big unanswered questions. By hurling neutrons at materials such as ice cores, metals and proteins, researchers can study past climates, detect weak points in gas pipes and understand how flour transforms into pastry.

''Neutrons have this wonderful ability to get inside different materials so we can look at complex structures,'' Dr Paterson said. He oversees 1200 staff, including about 300 PhD students.

But the nuclear organisation has not been without controversy. It was criticised over an accident in August 2008, when a vial of radioactive material was dropped and the incident was not reported for some hours.

Australia's workplace health and safety regulator, Comcare, concluded the incident had put staff at risk and, while it found ANSTO had adequately assessed the risk, it had not taken adequate steps to control that risk at the time of the incident.

Some people also link accidents at nuclear power stations, such as the meltdown in 2011 at the Fukushima plant in Japan, to research reactors. During the Fukushima accident, ANSTO engaged the public over the differences between research and power reactors.